Analog Devices Ltd

The LT3795 is a 110V, high-side current sense DC/DC converter designed to regulate a current or voltage to a constant value, ideal for driving high brightness (HB) LEDs. Its 4.5V to 110V input voltage range makes it appropriate for a wide variety of applications, including automotive, industrial and architectural lighting. This converter uses an external low side N-channel MOSFET and can drive up to 90V of white LEDs from a nominal 12V input, delivering in excess of 50 watts. Spread spectrum frequency modulation reduces EMI emissions, while an internal PMOS switch driver delivers robust short-circuit protection in boost and buck-boost topologies. The LT3795 incorporates a high-side current sense, enabling it to be used in boost, buck, buck-boost or SEPIC topologies. Additionally it offers current both input and output current limiting and monitoring for added reliability and design flexibility. It can deliver efficiencies of over 94% in boost mode, minimizing the need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz, optimizing efficiency while minimizing external component size and cost offering a very compact HB LED driver or charger solution. The LT3795 uses PWM dimming, which delivers constant LED color with dimming ranges of up to 3,000:1. For less demanding dimming requirements, the CTRL pin can be used to offer a 10:1 analog dimming range. Its fixed frequency, current mode architecture offers stable operation over a wide range of supply and output voltages. Robust open and short-circuit protection maximize overall system reliability. The LT3795 is available in a thermally enhanced TSSOP-28 package, pricing starts at $3.45 each in 1,000-piece quantities. An extended temperature version is priced at $3.86 each and a high temperature version starts at $4.11 each.

The LTC400-1 is a high voltage controller and power manager with input maximum power point control (MPPC) that converts virtually any externally compensated DC/DC power supply into a full-featured battery charger. This controller is capable of driving typical DC/DC converter topologies, including buck, boost, buck-boost, SEPIC, flyback and forward. The device offers precision input current monitoring and charge current monitoring and regulation. It operates across a wide 3V to 60V input and output voltage range, compatible with a variety of different input voltage sources, battery stacks and chemistries including lithium-ion/polymer/phosphate, sealed lead acid (SLA) and nickel-based. The LTC4000-1's MPPC circuit features an input voltage regulation loop that controls charge current to maintain the input voltage at a programmed level, ideal for solar panels or other high impedance sources. Applications include: high power battery charger systems, high performance portable instruments, battery backup systems, and industrial or military battery-equipped devices.The LTC4000-1 features an intelligent PowerPath topology that preferentially provides power to the system load when input power is limited. It controls external PFETs to provide low loss reverse current protection, efficient charging and discharging of the battery, and instant-on operation to ensure that system power is available at plug-in, even with a deeply discharged battery. External sense resistors and precision sensing ensure accurate currents at high efficiency, allowing operation with converters that span a wide power range. The LTC4000-1 is housed in low profile (0.75mm) 28-pin 4mm x 5mm QFN and 28-lead SSOP packages and is guaranteed for operation from -40°C to 125°C. 1,000-piece pricing starts at $3.95 each.

The LTC3863 is a high voltage inverting DC/DC controller that uses just a single inductor to produce a negative voltage from a positive input voltage.Most low to medium power inverters utilise a coupled inductor topology, or transformer which increases the circuit size and complexity.This device simplifies the design further with all of its interface signals being positive ground referenced. None of the LTC3863 pins are connected to a negative voltage allowing the output voltage to be limited only by the selection of external components.The LTC3863, operating over a 3.5V to 60V input supply range, is designed to protect against high voltage transients, to operate continuously during automotive cold crank and cover a broad range of input sources and battery chemistries.This device helps increase the run-time in battery-powered applications with its low 70µA quiescent current in standby mode with the output enabled in Burst Mode operation. The LTC3863's output voltage can be set from -0.4V to -150V or lower at up to 3A typical; making it well suited for 12V or 24V automotive, heavy equipment, industrial control, robotic and telecom applications.The LTC3863 drives an external P-channel MOSFET, operates with a selectable fixed frequency between 50kHz and 850kHz and is synchronizable to an external clock from 75kHz to 750kHz. Its current-mode architecture provides easy loop compensation, fast transient response, cycle-by-cycle over current protection and excellent line regulation.The LTC3863 is offered in 12-pin thermally enhanced MSOP and 3mm X 4mm QFN packages. The industrial grade versions operate from -40°C to 125°C junction temperature. The H-grade version is guaranteed to operate from -40°C to 150°C while the high reliability version is guaranteed from -55°C to 150°C. The 1,000-piece price starts at $2.06 each.

The LT4275 is a LTPoE++, PoE+ and PoE-compliant powered device (PD) interface controller for applications requiring up to 90W of delivered power. PoE+ limits the maximum PD power delivery to 25.5W, which is insufficient to power today's new class of power-hungry applications, such as picocells, base stations, signage and heated outdoor cameras. Linear Technology's LTPoE++ standard addresses this market by expanding the power budget to four different power levels 38.7W, 52.7W, 70W and 90W enabling complete high power LTPoE++ systems. The LTPoE++ standard employs a classification scheme that simply enables LTPoE++ power sourcing equipment (PSE) controllers and LTPoE++ PD controllers to reliably communicate with one another while maintaining interoperability with IEEE standard equipment. The LT4275A (LTPoE++), LT4275B (PoE+) and LT4275C (PoE) efficiently deliver power to PD loads using just one IC.Unlike traditional PD controllers that integrate the power MOSFET, the LT4275 controls an external MOSFET to drastically reduce overall PD heat dissipation and maximize power efficiency, especially important at higher power levels. This novel approach allows users to size the MOSFET to their application's specific heating and efficiency requirements, enabling the use of low RDS(ON) 30mOhm MOSFETs if necessary. The LT4275 recognizes a PSE as either Type 1 hardware complying with the IEEE 802.3af 13W power level, Type 2 hardware, complying with IEEE 802.3at 25.5W power level or LTPoE++ hardware complying with 38.7W to 90W power levels, and passes power accordingly. The LT4275 is offered in industrial and automotive grades supporting operating temp ranges from -40°C to 85°C and -40°C to 125°C. It is available in small 10-pin MSOP or 3mm x 3mm DFN packages and is priced starting at $1.45 each in 1,000-piece quantities.

The LT4320 is an ideal diode bridge controller for 9V to 72V systems that replaces each of the four diodes in a full-wave bridge rectifier with a low loss N-channel MOSFET to significantly reduce the power dissipation and increase available voltage.
Power supply size is reduced as the enhanced power efficiency eliminates bulky heat sinks. Low voltage applications benefit from the extra margin afforded by saving the two diode drops inherent in diode bridges. Compared to the traditional alternative, the MOSFET bridge enables a rectifier design that is highly space- and power-efficient. The controller operates from DC to 600Hz.
The LT4320 switch control smoothly turns on the appropriate two MOSFETs, while keeping the other two off to prevent reverse currents. An integrated charge pump provides the gate drive for the external low on-resistance N-channel MOSFETs without requiring external capacitors. The choice of MOSFETs offers the greatest flexibility in power levels ranging from one to thousands of watts.
The LT4320 is available in two options: the LT4320 is designed for DC to 60Hz voltage rectification, whereas the LT4320-1 rectifies DC to 600Hz.
Specified over the -40°C to 85°C industrial temperature range, the LT4320 is offered in a compact 8-pin 3mm x 3mm DFN package, and a 12-lead MSOP package with enhanced high-voltage pin spacing.
Priced beginning at $2.95 each for 1,000-piece quantities, the device is available today in production quantities. Evaluation circuit boards are available online or from your local Linear Technology sales office.
For more information, visit www.linear.com/product/LT4320.

The LT4320 is an ideal diode bridge controller for 9V to 72V systems that replaces each of the four diodes in a full-wave bridge rectifier with a low loss N-channel MOSFET to significantly reduce the power dissipation and increase available voltage.Power supply size is reduced as the enhanced power efficiency eliminates bulky heat sinks. Low voltage applications benefit from the extra margin afforded by saving the two diode drops inherent in diode bridges. Compared to the traditional alternative, the MOSFET bridge enables a rectifier design that is highly space- and power-efficient. The controller operates from DC to 600Hz.The LT4320 switch control smoothly turns on the appropriate two MOSFETs, while keeping the other two off to prevent reverse currents. An integrated charge pump provides the gate drive for the external low on-resistance N-channel MOSFETs without requiring external capacitors. The choice of MOSFETs offers the greatest flexibility in power levels ranging from one to thousands of watts.The LT4320 is available in two options: the LT4320 is designed for DC to 60Hz voltage rectification, whereas the LT4320-1 rectifies DC to 600Hz.Specified over the -40°C to 85°C industrial temperature range, the LT4320 is offered in a compact 8-pin 3mm x 3mm DFN package, and a 12-lead MSOP package with enhanced high-voltage pin spacing.Priced beginning at $2.95 each for 1,000-piece quantities, the device is available today in production quantities. Evaluation circuit boards are available online or from your local Linear Technology sales office.

The LTC4290/LTC4271 is an isolated 8-port power source equipment (PSE) controller chipset designed for use in IEEE 802.3at (PoE+) Type 1- and Type 2-compliant Power-over-Ethernet (PoE) systems.This chipset provides 8 independent PSE channels for simpler lower component count designs, reduced board space and ultimately reduced total solution costs.The LTC4271 provides a digital interface to the PSE host, whereas the LTC4290 provides the high voltage Ethernet interface; the two ICs are then bridged by an inexpensive Ethernet transformer.The transformer-isolated communication protocol replaces up to six expensive opto-couplers and a complex isolated 3.3V supply used in traditional designs, resulting in significant cost savings and a more robust and easy to manufacture design.This chipset earns a 100% interoperability score for PoE+ and PoE systems in popular compliance tests. When paired with the LT4275 PD (powered device) controller, complete end-to-end LTPoE++ systems can deliver up to 90W while remaining fully compatible with PoE+ and PoE.Users will appreciate the robustness provided by 80V port pins and lowest-in-industry power dissipation, making thermal design significantly easier than when designing with PSEs integrating more fragile normally-higher-RDS(ON) MOSFETs. The LTC4290 is offered in three power grades: 'A' grade uses Linear Technology's LTPoE++ signaling to support 38.7W, 52.7W, 70W and 90W PDs; 'B' grade uses PoE+ signaling to support up to 25.5W PDs; and 'C' grade uses PoE signaling to support up to 13W PDs. All chipsets are offered in industrial temperature ranges.The LTC4290 is in a RoHS-compliant 40-pin 6mm x 6mm QFN package, while the LTC4271 is in a 24-pin 4mm x 4mm QFN package. The LTC4290/71 chipset is priced starting at $10.00 each in 1,000 piece quantities.

The LT®1248 provides active power factor correction for universal off-line power systems. By using fixed high frequency PWM current averaging, without the need for slope compensation, the LT1248 achieves far lower line current distortion with a smaller magnetic element than systems that use either peak-current detection or zero current switching approaches in both continuous and discontinuous modes of operation. The LT1248 uses a multiplier containing a square gain function from the voltage amplifier to reduce the AC gain at light output load and thus maintains low line current distortion and high system stability. The LT1248 also provides filtering capability to reject line switching noise which can cause instability when fed into the multiplier. Line current dead zone is minimized with low bias voltage at the current input to the multiplier. The LT1248 provides many protection features including peak current limiting and overvoltage protection, and can be operated at frequencies as high as 300kHz.

The 8-pin LT®1249 provides active power factor correction for universal offline power systems with very few external parts. By using fixed high frequency PWM current averaging without the need for slope compensation, the LT1249 achieves far lower line current distortion, with a smaller magnetic element than systems that use either peak current detection or zero current switching approach, in both continuous and discontinuous modes of operation.The LT1249 uses a multiplier containing a square gain function from the voltage amplifier to reduce the AC gain at light output load and thus maintains low line current distortion and high system stability. The LT1249 also provides filtering capability to reject line switching noise which can cause instability when fed into the multiplier. Line current dead zone is minimized with low bias voltage at the current input to the multiplier.The LT1249 provides many protection features including peak current limiting and overvoltage protection. The switching frequency is internally set at 100kHz.While the LT1249 simplifies PFC design with minimal parts count, the LT1248 provides flexibilities in switching frequency, overvoltage and current limit.

The LT1339 is a high power synchronous current mode switching regulator controller. The IC drives dual N-channel MOSFETs to create a single IC solution for high power DC/DC converters in applications up to 60V. The LT1339 incorporates programmable average current limiting, allowing accurate limiting of DC load current independent of inductor ripple current. The IC also incorporates user-adjustable slope compensation for minimization of magnetics at duty cycles up to 90%. The LT1339 timing oscillator operating frequency is programmable and can be synchronized up to 150kHz. Minimum off-time operation provides main switch protection. The IC also incorporates a soft start feature that is gated by both shutdown and undervoltage lockout conditions. An output phase reversal pin allows flexibility in configuration of converter types, including inverting and negative topologies.